Despite a large number of studies on tick biology, there is limited information on long- term changes in tick populations. This study thus aimed to assess the long-term population dynamics of questing ixodid ticks in two landscape zones of the Kruger National Park (KNP). Questing ixodid ticks were collected in the KNP from August 1988 to March 2002 by monthly dragging of the vegetation in three habitats (grassland, woodland and gully) at two sites (Nhlowa Road and Skukuza). Findings pertaining to total tick numbers and Amblyomma hebraeum and Rhipicephalus decoloratus specifically are presented here. Fourteen tick species were collected, as well as four others that could be identified only to generic level. More ticks (211 569 vs 125 810) were collected at Nhlowa Road than at Skukuza. Larvae were the most commonly collected stage of all the major tick species. A. hebraeum was the most commonly collected tick (63.6%) at Nhlowa Road, whereas R. decoloratus accounted for 15.3% of the ticks collected there. At Skukuza, 31.6% and 27.1% of the collected ticks were R. decoloratus and A. hebraeum respectively. Most A. hebraeum larvae were collected in summer and the fewest in winter and early spring, mostly in woodland and least often in grassland habitats. Most R. decoloratus larvae were collected in spring and the fewest in autumn and winter, and were more frequently collected in woodland and grassland than in gullies. The largest collections of most tick species were made during the early 1990s, while numbers were lowest in the mid-1990s after a drought during 1991 and 1992 and then increased towards the late 1990s, followed by a final decrease. The changes in tick numbers over time probably reflect differences in their host communities at the two sites and the effect of climatic conditions on both hosts and free-living ticks. The population dynamics of questing ticks reflect a complex interaction between ticks, their hosts and the environment.

Ticks, as vectors of disease and damage agents, impact directly and indirectly on the economy of the livestock industry in southern Africa. This study surveyed the occurrence and distribution of ticks infesting livestock across the North West province, South Africa. During three phases in consecutive years, officers of the provincial Veterinary Department collected specimens monthly from livestock hosts at specified sites across the province. Data analysis constituted the fourth phase of the study. A total of 1090 collections from 265 sites yielded 42 566 tick specimens, comprising 22 different tick species (18 ixodids, 4 argasids). The specimens represent all of the major tick vectors of disease that occur in South Africa. The major tick-borne diseases (i.e. heartwater, both African and Asiatic bovine babesiosis and anaplasmosis) were found to be prevalent mainly in the north-eastern region of the province, which also displayed the highest tick species diversity. The central region appears transitory to some of the major vectors. Although some tick species were contained within specific regions, others were widespread across the province. Associated serology data show that most herds sampled in areas endemic for babesiosis and anaplasmosis in the north-eastern region are endemically unstable and at risk to these tick-borne diseases should vector control measures become ineffective.

Amblyomma hebraeum, percentage and rate of female attachment to rabbits was higher (except shortly after release of females) around feeding males than in areas previously treated with extract of fed males, effect of elapsed time and of number of males vs. equivalent extract on attachment values, results prove bioassays to be valid for component and extract-equivalent assessment

Theileria mutans, 4 isolates obtained from geographically distant parts of South Africa by subinoculation of infected blood were readily transmitted to cattle by Amblyomma hebraeum, all attempts to transmit these isolates with Rhipicephalus appendiculatus were unsuccessful

Amblyomma hebraeum, 60CO irradiation of nymphs failed to attenuate Cowdria ruminatium

Amblyomma maculatum, experimental vector of Cowdria ruminantium in goats, other Amblyomma spp. unsuccessful; Theileria mutans in calves transmitted by Amblyomma variegatum, but not by other Amblyomma spp.

Amblyomma hebraeum, purification procedure used to obtain pure toxic components of tick eggs, characterization of toxin structure, histopathologic lesions observed in guinea pigs inoculated with egg extract or purified toxin, lesions in guinea pigs inoculated with crude egg extracts of 3 other ticks were histopathologically similar